We study the structure and stability of closed ring carbon nanotubes
using a theoretical model based on the Brenner-Tersoff potential. Many
metastable structures can be produced. We focus on two methods of
generating such structures. In the first, a ring is formed by
geometric folding and is then relaxed into minimum energy using a
minimizing algorithm. Short tubes do not stay closed. Yet tubes
longer than 18 nm are kinetically stable. The other method starts
from a straight carbon nanotube and folds it adiabatically into a
closed ring structure. The two methods give strikingly different
structures. The structures of the second method are more stable and
exhibit two buckles, independent of the nanotube length. This result
is in strict contradiction to an elastic shell model. We analyze the
results for the failure of the elastic model.
PACS: 61.46.+w, 73.22.-f, 62.25.+g, 64.70.Nd.
Download the paper in PDF format |